"Microsoft Shuts Down MSIX Protocol to Block Malware Exploits"
Originally Published 2 years ago — by TechRadar

Microsoft has taken action to disable the ms-appinstaller protocol handler by default due to its exploitation by hackers to deploy malware, including ransomware. The company observed four threat actors, including Storm-0569 and FIN7, using the handler to bypass security mechanisms and distribute malware through fake ads and phishing via Microsoft Teams. The handler is now disabled in App Installer version 1.21.3421.0 or higher to prevent further abuse. This follows previous incidents where MSIX files were used for malware distribution, highlighting ongoing cybersecurity challenges.
